1. Field of the Invention
The present invention relates to a solid-state image pickup device such as a charge-coupled device (CCD) image sensor and a CMOS image sensor, and the solid-state image pickup device is used in, for example, a mobile-phone having an image sensor, a digital camera, and a video camera.
2. Description of the Related Art
As for the image sensor, in recent years, miniaturization of pixels has advanced, pixels of a size from 2.0 to 2.9 μm have already been put into practical use, and development of 1.7- and 1.4-μm pixels is now underway. In a minute pixel having a size of 2 μm or less, an amount of incident light largely decreases, and hence the signal-to-noise ratio is decreased. Further, heretofore, in a color camera, there has been a problem that an image quality is deteriorated due to a color artifact or color noise. Regarding suppression of a color artifact and noise reduction, various methods have been proposed (see, for example, Jpn. Pat. Appln. KOKAI Publication No. 4-235472, Jpn. Pat. Appln. KOKAI Publication No. 2002-10108, Jpn. Pat. Appln. KOKAI Publication No. 2005-303731, Jpn. Pat. Appln. KOKAI Publication No. 2001-245307, and Jpn. Pat. Appln. KOKAI Publication No. 5-168029). However, radical measures are not proposed.